Recently used endoscope apparatuses (endoscope systems) use image sensors with a large number of pixels, leading to a shallow depth of field and thus rendering focus adjustment operation for conventional manual focusing (hereinafter, referred to as MF) difficult for users. In view of this, endoscope apparatuses featuring auto focus (hereinafter, referred to as AF) control have been developed.
Lens control (focus lens control) for MF or AF requires lens movement speed or a lens movement amount per unit time (hereinafter, referred to as a step amount) to be appropriately set based on optical characteristics. This is for shortening time required for bringing a subject into focus, and for preventing an unstable operation due to the peak point missed.
Some endoscope apparatuses have a configuration in which a rigid scope serving as an interchangeable optical system is attached to a main body including an image capturing section. Such an interchangeable optical system to be attached can be selected from numerous optical systems.
In JP-A-2005-250127, the shortest possible focusing time is achieved for an AF operation without impairing stability by calculating an appropriate step amount based on an aperture stop status and a zoom lens position obtained by a potentiometer.
In JP-A-2010-35131, a specific lens type is determined based on whether vignetting occurs if the zoom lens position is on the wide angle end side relative to a conversion lens the lens information of which cannot be obtained through an electrical contact and whether the vignetting can be reduced by moving the zoom lens position toward the telephoto end side from the wide angle end side. The settings related to image capturing are changed according to the type determined.